1,6-Dibromohexane: Properties, Uses & Lab Handling Guide

1,6-Dibromohexane is a symmetric α,ω-dibromoalkane widely used in organic synthesis as a bifunctional alkylating and cross-linking reagent.

CAS Number

629-03-8

Molecular Formula

C₆H₁₂Br₂

Molecular Weight

243.97 g/mol

Appearance

Colorless to pale yellow liquid

Boiling Point

approximately 240 °C (at 760 mmHg)

Density

approximately 1.59 g/mL at 25 °C

Solubility

Miscible with common organic solvents (DMF, THF, acetone, dichloromethane); practically insoluble in water

Storage Condition

Store in a cool, dry, well-ventilated area, away from heat and ignition sources

Chemical Identity and Physical Properties

1,6-Dibromohexane (CAS 629-03-8; synonyms: hexamethylene dibromide, 1,6-hexanediyl dibromide) is a straight-chain dihalide with the molecular formula C₆H₁₂Br₂ and a molecular weight of approximately 243.97 g/mol. It presents as a colorless to pale-yellow liquid with a characteristic halogenated-solvent odor. Key physical constants include a boiling point of approximately 240 °C at atmospheric pressure and a density of approximately 1.59 g/mL at 25 °C. The compound is practically insoluble in water but freely miscible with polar aprotic solvents such as DMF and DMSO, as well as common organic solvents including THF, acetone, and dichloromethane. Its symmetric structure—two reactive primary alkyl bromide termini separated by a flexible six-carbon chain—makes it an ideal bifunctional building block for a wide range of synthetic transformations.

Synthetic Applications and Research Uses

1,6-Dibromohexane is extensively employed across diverse areas of synthetic and materials chemistry owing to its two highly reactive primary C–Br bonds, which participate readily in S_N2 substitution, elimination, and metal-mediated coupling reactions. Principal research applications include:

• Macrocycle and ring synthesis: The six-carbon tether is a common spacer in the preparation of cyclic ethers, lactams, and macrocyclic compounds via intramolecular cyclization.
• Polymer and cross-linker synthesis: The reagent serves as a difunctional monomer or cross-linking agent in the preparation of polyethers, polysulfides, polyamines, and dendrimers. It is widely used to introduce flexible hexamethylene spacers into polymer backbones.
• N-Alkylation and O-alkylation: Amines, alcohols, phenols, and thiols can be mono- or bis-alkylated to install hexyl-linker motifs for pharmaceutical intermediates, ionic liquids, and surfactant synthesis.
• Grignard and organolithium preparation: Treatment with magnesium or lithium metal affords bifunctional organometallic intermediates useful in carbon–carbon bond-forming reactions.
• Surface functionalization: Used to tether functional groups onto silica, gold, and polymer surfaces in materials science and sensor development.
• Pharmaceutical and agrochemical building blocks: Acts as a methylene-chain extender for synthesizing biologically active molecules and prodrug linkers.

Typical reaction conditions employ a base (K₂CO₃, NaH, or Et₃N) in a polar aprotic solvent at temperatures ranging from room temperature to 80 °C, with careful stoichiometric control to minimize bis-alkylation when mono-substitution is desired.

Safety, Handling, and Regulatory Considerations

1,6-Dibromohexane is a lachrymatory and irritating liquid that poses inhalation, skin absorption, and eye-contact hazards. Researchers must consult the current Safety Data Sheet (SDS) before use. Key precautions include:

• Personal Protective Equipment (PPE): Chemical-resistant gloves (nitrile or neoprene), splash-proof safety goggles, and a laboratory coat are mandatory. Work in a certified chemical fume hood to prevent vapor inhalation.
• Skin and eye contact: In case of contact, flush immediately with copious water for at least 15 minutes and seek medical attention. Remove contaminated clothing promptly.
• Alkylating agent hazard: As a bifunctional alkylating agent, 1,6-dibromohexane may pose mutagenic risks. Handle with appropriate caution; minimize exposure duration and frequency.
• Fire and reactivity: The compound is combustible. Keep away from open flames, strong oxidizers, and reactive metals. Have appropriate dry-chemical or CO₂ fire extinguishers accessible.
• Waste disposal: Dispose of waste in accordance with local, national, and institutional regulations for halogenated organic waste. Do not pour down the drain.
• Regulatory status: Users should verify current regulatory status in their jurisdiction; dibromoalkanes may be subject to reporting or restriction under various chemical management frameworks.

Storage, Stability, and Quality Considerations

Proper storage of 1,6-dibromohexane is essential to maintain reagent quality and ensure safe handling over the shelf life of the product. Recommended storage and stability guidelines include:

• Temperature: Store at room temperature (15–25 °C) in a cool, dry, well-ventilated location, away from direct sunlight and sources of heat or ignition.
• Container: Keep in the original tightly sealed amber glass or high-density polyethylene (HDPE) container to minimize light exposure and moisture ingress.
• Incompatibilities: Avoid contact with strong bases, strong oxidizing agents, reactive metals (Na, K, Mg), and moisture, which can promote hydrolysis or violent reactions.
• Stability: The compound is generally stable under recommended storage conditions. However, prolonged exposure to light, heat, or moisture may cause discoloration or partial degradation. Discard visibly discolored or turbid material after verification.
• Purity verification: For critical synthetic applications, verify purity by GC or ¹H NMR prior to use. Aladdin Scientific's product D106541 is supplied at high purity suitable for research-grade applications.
• Shelf life: Follow the expiry date indicated on the product label; conduct periodic purity checks for long-stored material.

Frequently asked questions

What solvents are recommended for reactions using 1,6-Dibromohexane?

Polar aprotic solvents such as DMF, DMSO, acetonitrile, and THF are most commonly recommended, as they solubilize both the reagent and typical nucleophilic partners (amines, alkoxides, thiolates) while promoting S_N2 reactivity. Dichloromethane is suitable for reactions at lower temperatures. Water should be avoided due to the reagent's insolubility and susceptibility to hydrolysis under strongly basic conditions.

How can I minimize bis-alkylation when using 1,6-Dibromohexane for mono-functionalization?

To favor mono-alkylation, use a large excess (2–5 equivalents) of the nucleophile relative to 1,6-dibromohexane so that each molecule of dibromoalkane reacts predominantly at one end. Alternatively, add the dibromoalkane slowly (dropwise) to a solution of the nucleophile under dilute conditions to minimize the probability of a second intramolecular or intermolecular substitution. Temperature control and careful monitoring by TLC or GC can further optimize selectivity.

Is 1,6-Dibromohexane compatible with Grignard reaction conditions?

Yes, 1,6-dibromohexane can react with magnesium turnings in anhydrous THF or diethyl ether to form the corresponding bifunctional Grignard reagent, though formation of cyclic or polymeric by-products via intramolecular Wurtz coupling can be a competing pathway. Highly dilute conditions and slow addition of the dibromoalkane to activated magnesium are typically employed to mitigate these side reactions. Rigorous exclusion of moisture and oxygen is mandatory for successful Grignard reagent preparation.

What are the main health hazards associated with 1,6-Dibromohexane?

1,6-Dibromohexane is irritating to the skin, eyes, and respiratory tract, and inhalation of its vapors should be strictly avoided. As a bifunctional alkylating agent, it may pose mutagenic risks with repeated or prolonged exposure. Always work in a fume hood, wear appropriate PPE (chemical-resistant gloves, safety goggles, and lab coat), and consult the current SDS for detailed hazard information and first-aid measures.

What purity grade of 1,6-Dibromohexane does Aladdin Scientific offer?

Aladdin Scientific supplies 1,6-Dibromohexane under SKU D106541 at a research-grade purity suitable for synthetic chemistry and related laboratory applications. For exact purity specifications and certificate of analysis details, please refer to the product page or contact Aladdin Scientific's technical support team.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992. (General reference for S_N2 reactivity of alkyl halides and bifunctional reagents.)
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (Textbook-level discussion of dihalide reactivity, macrocyclization, and cross-linking strategies.)
3. Sigma-Aldrich / Merck. Safety Data Sheet: 1,6-Dibromohexane (CAS 629-03-8). (Referenced for general physical property and hazard data; verify against Aladdin Scientific SDS for product-specific data.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.